Patent Document 1 discloses a sealing structure where double O-rings are provided on an inside and outside of a housing sealing surface of a vehicle refrigerant compressor such that corrosive components such as moisture, salt, or the like are suppressed from penetrating between sealing surfaces to prevent generation of corrosion in the sealing surfaces.
Patent Document 2 discloses a sealing structure where an O-ring and circular packing material are doubly provided inside and outside on a flange sealing surface of a sealed container sealing electric power equipment, and penetration of rainwater or the like is prevented by a circular packing material on an outer circumferential side such that air tightness is maintained by the O-ring on an inner circumferential side.
In general, in a case where a housing sealing surface, flange sealing surface, or the like is sealed using an O-ring, the filling ratio of the O-ring inside an O-ring groove formed on the sealing surface, in other words, the ratio of the O-ring volume (cross-sectional area) with regard to the internal volume (cross-sectional area) of the O-ring groove is estimated to have a median value of a set reference range of approximately 75%, and a maximum value of 90% or less.